Electron-proton synergy driven photocatalytic coupling for H₂O₂ and C3 production by an S-scheme CdS/CN...

Photocatalytic hydrogen peroxide (H₂O₂) production presents a sustainable alternative to the energy-intensive anthraquinone process. However, its efficiency is limited by rapid charge recombination, and the need for sacrificial agents poses challenges for practical deployment. Herein, we develop an S-scheme cadmium sulfide/graphite phase carbon nitride (CdS/CN) heterojunction for H₂O₂ photosynthesis coupled with glycerol (GLY) oxidation. The optimized CdS/CN demonstrates enhanced charge separation due to interfacial band bending and internal electric fields, achieving a 10.75-fold higher H₂O₂ yield (3.01 mM) than pristine CN (0.28 mM). Moreover, GLY serves as a dual mediator that enables electron-proton synergy within the photocatalytic system, by acting as both a hole scavenger and a proton donor, effectively increasing H₂O₂ production while simultaneously undergoing selective oxidation to yield high-value C3 oxidation derivatives such as dihydroxyacetone (DHA) and glyceraldehyde (GLAD), with >99% selectivity. Mechanism studies reveal that the photogenerated electrons drive two-electron O₂ reduction to H₂O₂ while holes promote GLY oxidation. This electron-proton synergistic coupling system enables simultaneous solar-driven H₂O₂ production and the selective oxidation of biomass, offering a sustainable pathway for green chemical manufacturing.